Some Misunderstandings Related to WTC Collapse Analysis

[Lauren Johnson]

Tony said this @101.

You have it right about there not being enough heat to cause what we observed. The NIST didn't find evidence of high temperatures on the steel. They only found three pieces out of the 236 they got from the twin towers that had even seen temperatures beyond 250 degrees C, where steel hasn't even begun to lose strength.

It isn't just that the collapse couldn't have started because there wasn't enough heat. There is another clue that it was unnatural as the acceleration through the first story was constant at 5.1 m/s^2. In a natural heat weakening situation the columns would have been softened to the point where they just couldn't handle the load when they began to fall. With constant acceleration, the average resistance should have been the strength just below where yield would start. So it should have been quite slow, but it was not. The observations of constant and rapid acceleration through the first story, along with the point that in a natural situation the fall would start when the columns would have been heated to where they just started to yield, are not consistent with heat weakening in a natural collapse.

Your point here Tony cannot be emphasized enough.